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Telopea Vol. 6(4): 1996 
Ecological features: Known from only two locations on remnant ironstone within 
seasonally inundated heath at Scott River and Ruabon. Plants are killed by fire and 
regenerate from seed. 
Conservation status: Rare and endangered, apparently restricted to two unreserved, 
small populations on ironstone pavement habitats. 
Etymology: The specific epithet is from the Latin rnagnus, great, referring to the large 
size of adult clumps. 
Onychosepalum microcarpum K. A. Meney & J. S. Pate, sp. nov. 
Planta dioica, demissa, caespitosa, rhizomatibus pilis sparsis instructis, erectis, culmis 
laevibus, cylindraceis, sinuosis vel erectis, ramis absentibus, vaginis caulinis 1-2, 
striatis, apice nitidis, spiculis plerumque singulis atque terminalibus. 
Type: South-western Western Australia, S.W. Botanical Province, Gingin (31°21S 
115°54'E) to Cataby (30°45'S 115°33'E) Meney & Pate KM 9091, 6 September 90 (holotype 
KPBG; isotype PERTH). Growing in deep sand. 
Habit: Plants dioecious, diminutive, 7-15 cm tall, tufted. Rhizome ascending, 
0.5-0.8 mm wide, axillary rooting at nodes; internodes sparsely tomentose, reddish- 
brown with tufts projecting beyond scale leaves; scale leaves straw-coloured, crowded, 
overlapping, ovoid-triangular with prominent striations, 2-3 mm long; cataphylls 
straw-coloured, 3-5 mm long, ridged, broadly ovate; mucro prominent, 1-2 mm 
long. Culms terete, smooth, unbranched 0.3-0.5 mm wide, sinuose in females to 
more erect in males; culm sheaths 1-2 per culm, light green-brown, striate, 4-6 mm 
long; lamina broad, flared, 2-5 mm long. Male spikelets usually solitary and terminal 
on the culm, occasional culms with a second smaller spikelet arising from the node, 
ovoid globose, 4-6 mm long, 3—4 mm broad; inflorescence bracts similar to glumes; 
glumes light brown, broadly lanceolate, 2-2.5 mm long, the lower 7-12 glumes 
sterile; mucro dark brown 0.5-1 mm long. Male flowers sessile, 10-20 per spikelet; 
tepals 6, straw-coloured, 1.8-2 mm long, linear, membranous with blunt apex. Female 
spikelets narrow-ovoid, 3-4 mm long, 1-1.3 mm broad, 2-3 per culm; inflorescence 
bracts pale straw-coloured, 1-1.2 mm long; apex exceeding the length of each bract, 
up to 2 mm; glumes 1.5-2.5 mm with scarious margins carrying a fringe of hairs, 
lower 6-8 glumes sterile; mucro 0.8-1.2 mm long. Female flowers 1-2 terminal flowers 
per spikelet; tepals 6, 0.8-1 mm long, mucronate, transparent, scarious, broadly 
lanceolate; style 7-8 mm long, undivided; stigma single, purple, exserted 5 mm 
beyond the spikelet; ovary unilocular. Fruit a diminutive nut, less than 0.5 mm long. 
Flowering: August-October. Seed-shed: September-October. Seedlings: similar to 
adult plants. 
Affinities: This species is closely similar to Onychosepalum laxiflorum Steud. but 
differs in possessing diminutive spikelets, usually with several spikelets on each 
female culm and with several (as opposed to one) internodes per culm. Flower and 
fruit characteristics are broadly similar to those of Lepidobolus and Catacolea. 
Ecological features: Onychosepalum microcarpum is known from three small populations 
in the Northern Sandplains between Gingin and Badgingarra. It is a short-lived 
opportunistic species which colonises bare areas of leached deep white and yellow 
sand, particularly after disturbance. It does not contain appreciable reserves of starch 
and plants are killed by fire. No information is available on seed longevity. 
Conservation status: Conservation status is uncertain. It appears locally abundant 
but requires further study in view of the restricted distribution and ephemeral nature 
of the presently known populations. 
Etymology: The specific epithet microcarpum is from the Greek mikros, small and 
karpos, a fruit, referring to the small fruits of the species. 
